Such a circuit arrangement is a DC-AC-converter of the bridge type and is often used for the operation of both high pressure discharge lamps as well as low pressure discharge lamps. The circuit arrangement can be a full bridge or a half bridge. A half bridge comprises only two switching elements, since the first circuit element A and the second circuit element B are both formed by capacitors. A full bridge, however, comprises four switching elements, since the first circuit element A and the second circuit element B are formed by a third and fourth switching element. In a full bridge the control circuit is more complicated than in a half bridge since the conductive state of four switching elements instead of only two switching elements needs to be controlled. During operation the amplitude of the voltage across the load circuit(s) in a full bridge is twice as high as it is in a half bridge powered by the same supply voltage source. As a consequence a full bridge can be used to operate two lamps in series so that each of the lamps carries the same current. In case the lamps have approximately the same lamp voltage, as is usually the case for low pressure discharge lamps, the lamps will approximately consume the same amount of power and have approximately the same light output. In case of high pressure discharge lamps, however, the lamp voltage depends strongly on the age of the lamp (age=number of burning hours). As a consequence the light outputs of two high pressure lamps operated in series can differ substantially when the lamps have a different age. The voltage across the load circuit of a half bridge powered by the same supply voltage source will generally not be high enough to operate such a series arrangement of lamps. A disadvantage of the full bridge is that, because of the two additional switches and the more complicated control circuit, it is more expensive than a half bridge. As an alternative for of operating two lamps in series in a fall bridge, two load circuits comprising a lamp and a ballast inductor each, can be connected in parallel in a half bridge. In case the lamps are low pressure mercury lamps that are operated with a high frequency lamp current, the lamp currents can be controlled at substantially equal values by making use of an equalizer transformer. However, such a transformer is an expensive component. In case the lamps are high pressure lamps operated by a low frequency AC current, an equalizer transformer cannot be used to control the lamp currents since the low frequency would demand a very big transformer. Nevertheless, in case no equalizer transformer is used, a difference in lamp voltage between the lamps will in practice often result in substantial differences in the amounts of power supplied to the lamps.